# Epic's GPUlightmass **URL:** \ **Category:** Rendering\ **Tags:** unreal-engine\ **Created:** [March 5, 2020, 12:52pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357 "2020-03-05T12:52:56Z")\ **Posts on this page:** 20\ **Page:** 48
**Author:** ![ph1rmacist](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ph1rmacist](https://forums.unrealengine.com/u/ph1rmacist)\ **Post date:** [July 15, 2026, 12:59pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/958 "2026-07-15T12:59:46Z")
A bug i found is that when **Use Area Shadows for Stationary Light** (In the directional light settings) is True while using a stationary directional light, separated meshes that use the same material get lines between them after moving some distance away from them: [![](https://d3kjluh73b9h9o.cloudfront.net/original/4X/6/d/f/6df977560ee30767d7f539f4253757e2be472619.jpeg "GPULightmass Bug") ](https://www.youtube.com/watch?v=AQwJdXhwP-I) Also increasing the r.screenpercentage makes the lines appear farther away This does not happen when using CPU Lightmass, And it does not happen when **Use Area Shadows for Stationary** **Light** is off I am using version 5.7.4 ---
**Author:** ![kotlet](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kotlet](https://forums.unrealengine.com/u/kotlet)\ **Post date:** [July 18, 2026, 1:56pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/959 "2026-07-18T13:56:09Z")
Thanks for the spotlight fix. ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 19, 2026, 8:25am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/960 "2026-07-19T08:25:37Z")
Looks like related to mip map selection. Could you send me a minimal repro project? ---
**Author:** ![ph1rmacist](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ph1rmacist](https://forums.unrealengine.com/u/ph1rmacist)\ **Post date:** [July 20, 2026, 3:06pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/961 "2026-07-20T15:06:33Z")
Here, Created Using version 5.7.4 > **[GPULightmass\_Bug.zip](https://drive.google.com/file/d/1yCMkpsXdmVLU3T0-jUJWNEdDdv4EsUjV/view?usp=drive_link)** > > Google Drive file. ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 23, 2026, 7:37am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/962 "2026-07-23T07:37:15Z")
# Release 5.8.0 2026.07.23 [A newer version is available below](https://forums.unrealengine.com/t/epics-gpulightmass/139357/984) [Back to release list](https://forums.unrealengine.com/t/epics-gpulightmass/139357/667) - Fix issue with stationary local light shadow invalid texel detection ![ScreenShot00000](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/9/0/29031ed173c20fa57860a5499dfb5c788a38cc19.png) @ph1rmacist I don’t have the disk space to host multiple engine variations so unfortunately I can’t provide you a drop-in installer for 5.7.4. So you need to either: - If you want to use 5.7.4 you’ll need to build from source. Use [https://github.com/AlanIWBFT/UnrealEngine/commit/2ec81b8838c6532720d94337272977fc5c6376d4](https://github.com/AlanIWBFT/UnrealEngine/commit/2ec81b8838c6532720d94337272977fc5c6376d4) as base then cherry pick [https://github.com/AlanIWBFT/UnrealEngine/commit/240a8cc6472c635c45edded8c5b7c1125242eeb4](https://github.com/AlanIWBFT/UnrealEngine/commit/240a8cc6472c635c45edded8c5b7c1125242eeb4) on top and build to get a fixed 5.7.4 engine build. - Or upgrade to 5.8.0 and use the installer provided. ---
**Author:** ![ph1rmacist](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ph1rmacist](https://forums.unrealengine.com/u/ph1rmacist)\ **Post date:** [July 23, 2026, 2:49pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/963 "2026-07-23T14:49:21Z")
Thank you so much for your work. ---
**Author:** ![kotlet](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kotlet](https://forums.unrealengine.com/u/kotlet)\ **Post date:** [July 26, 2026, 10:20am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/964 "2026-07-26T10:20:00Z")
Are there any plans to implement harmonic smoothing for VLM? Unfortunately without it lighting on movable characters is atrocious, way too directional and artificial. ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 26, 2026, 11:30am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/965 "2026-07-26T11:30:54Z")
I’ve actually looked into several approaches but each has its own trade-offs. If you’re interested, I can send you some versions to test. ---
**Author:** ![kotlet](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kotlet](https://forums.unrealengine.com/u/kotlet)\ **Post date:** [July 26, 2026, 12:15pm UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/966 "2026-07-26T12:15:51Z")
Please do. I will check them out. Because right now lack of smoothing VLMs out is kinda a showstopper. ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 27, 2026, 4:49am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/967 "2026-07-27T04:49:18Z")
@kotlet I have a question for you. Are you using static lights and the most of artifacts come from them? ---
**Author:** ![kotlet](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kotlet](https://forums.unrealengine.com/u/kotlet)\ **Post date:** [July 27, 2026, 5:50am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/968 "2026-07-27T05:50:08Z")
Messed up editing. ---
**Author:** ![Xathian](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Xathian](https://forums.unrealengine.com/u/Xathian)\ **Post date:** [July 27, 2026, 6:57am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/969 "2026-07-27T06:57:49Z")
When I run the installer on my UE\_58 directory I just get this error ![GPULM-5.8.0.tmp_2026-07-27_02-50-40](https://d3kjluh73b9h9o.cloudfront.net/original/4X/6/d/e/6de58fee43fbf86d6c59dbc28b9ee9f28643a54d.png) ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 27, 2026, 6:59am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/970 "2026-07-27T06:59:53Z")
I need a test scene from you as right now my most promising solution is for static lights only. ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 27, 2026, 7:00am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/971 "2026-07-27T07:00:51Z")
Verify your engine in the launcher and try again ---
**Author:** ![Xathian](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Xathian](https://forums.unrealengine.com/u/Xathian)\ **Post date:** [July 27, 2026, 7:05am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/972 "2026-07-27T07:05:59Z")
Same error. My InstalledBuild.txt does in fact say UE\_5.8 despite the error claiming it doesn’t ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 27, 2026, 7:17am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/973 "2026-07-27T07:17:05Z")
There should be a setup log in your %TEMP% folder like “Setup Log 2026-07-27 #001.txt”. You can send me the file and I’ll investigate. ---
**Author:** ![Xathian](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Xathian](https://forums.unrealengine.com/u/Xathian)\ **Post date:** [July 27, 2026, 7:35am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/974 "2026-07-27T07:35:13Z")
Yeah I was just digging out the temp files and attempting to just run the hdiffz patch manually but it’s still erroring out claiming the base UE\_5.8 install folder it’s targeting isn’t matching the directory the Patch.hdf is expecting, even though it’s a fresh, verified UE5.8 install directory [https://pastebin.com/pqTtUVmW](https://pastebin.com/pqTtUVmW) ---
**Author:** ![yujiang.wang](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@yujiang.wang](https://forums.unrealengine.com/u/yujiang.wang)\ **Post date:** [July 27, 2026, 7:43am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/975 "2026-07-27T07:43:47Z")
[HDiffZ.exe](https://forums.unrealengine.com/uploads/short-url/olwz2Qp06ZwZihX4KV3kWeuKz2L.exe) (1.4 MB) [Base.xxh128](https://forums.unrealengine.com/uploads/short-url/j8xmlceHjN13uAoda1lEvMZaA5I.xxh128) (69.6 KB) Then, run ```auto hdiffz "-M-check#Base.xxh128" "" ``` For your installation: ```auto hdiffz "-M-check#Base.xxh128" "E:\Programs\Epic Games\UE_5.8\" ``` It will then tell you where it encounters the error. Also, from the log, ```auto 2026-07-27 03:13:57.289 LauncherInstalled.dat has no entry for UE_5.8: C:\ProgramData\Epic\UnrealEngineLauncher\LauncherInstalled.dat ``` Your engine isn’t actually properly registered in the launcher. ---
**Author:** ![kotlet](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kotlet](https://forums.unrealengine.com/u/kotlet)\ **Post date:** [July 27, 2026, 7:50am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/976 "2026-07-27T07:50:09Z")
I will gut and prepare this scene. This is my scrapped character anyway so i can send this to you for testing, ill just try to rip textures out so its light. But before that lemme show you what I mean. This is with 50 lux sun. For some reason epics harmonic smoothing kicks in only at stronger lights. With 10 lux sun you would not see much difference. Sure the downside is that character is brighter a bit, but difference in shading quality is huge. Probably value of 3 would be more in the middle. 0.02 VLM smoothing: ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/e/7/e/e7e59d8dfd9ce8728114346659d149e0a4593b47.png) Smoothing set to 5: ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/b/a/8/ba8b47e48fd76d52b0b11312024eed6cc3de0a99.png) Pathtracer: ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/f/3/2f3829e587f5306daab5ace70fcecc50cbb4ee59.png) ---
**Author:** ![Xathian](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Xathian](https://forums.unrealengine.com/u/Xathian)\ **Post date:** [July 27, 2026, 8:09am UTC](https://forums.unrealengine.com/t/epics-gpulightmass/139357/977 "2026-07-27T08:09:48Z")
The command just returns > inputPath not exist ERROR! Even though the input path absolutely exists. I went and checked LauncherInstalled.dat and 5.8 is indeed not being added to it even when I reinstall (also the fact this is a json file is why I assume you have this jq.exe packed into the installer) [Previous page](https://forums.unrealengine.com/t/epics-gpulightmass/139357.md?page=47) [Next page](https://forums.unrealengine.com/t/epics-gpulightmass/139357.md?page=49)